Inquiry into LifeTwelfth Edition

Chapter 32

Lecture PowerPoint to accompany

Sylvia S. Mader

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

32.1 Nature versus Nurture: Genetic Influences

• Behavior

– Any action that can be observed and described

– Genes, to a degree, control behavior

32.1 Nature versus Nurture: Genetic Influences

• Experiments with Lovebirds, Snakes, and Snails– Lovebird Nesting Behavior

• Fischer lovebirds, Agapornis fischeri, cut strips from leaves and carry them to their nest site

• Peach-face lovebirds, Agapornis roseicollis, also cut strips but tuck them into their rump feather and carry them that way

• Hybrid lovebirds exhibit intermediate behavior. They cut strips and try to tuck them into feathers, but are unsuccessful

• These studies support the hypothesis that behavior has a genetic basis.

Nest Building Behavior in Lovebirds

32.1 Nature versus Nurture: Genetic Influences

• Experiments with Lovebirds, Snakes, and Snails– Garter Snake Experiments

• Genetic role in food preference– Inland populations of garter snakes are aquatic and feed

in the water on fish and frogs– Coastal populations are terrestrial and feed on slugs– In the laboratory, inland snakes refused slugs, while

coastal snakes readily accepted them» Hybrid snakes exhibited intermediate acceptance of

slugs as food

• This study suggests a genetic basis for feeding preference

Feeding Behavior in Garter Snakes

32.1 Nature versus Nurture: Genetic Influences

• Experiments with Lovebirds, Snakes, and Snails– Garter Snake Experiments

• Determined that sensory receptors are specific for prey – Researchers presented baby snakes with slug extract on cotton

swabs and then counted the number of tongue flicks

» Coastal snakes had a higher number of tongue flicks than inland snakes

» Apparently, coastal snakes have many receptors on their tongues for taste and smell of slugs, inland snakes do not

• A genetic difference between the two populations results in a physiological difference in nervous systems.

32.1 Nature versus Nurture: Genetic Influences

• Experiments with Lovebirds, Snakes, and Snails

– Snail experiments• Show role of endocrine system in behavior

• ELH- egg-laying hormone was isolated in Aplysia snails

• ELH controls all aspects of egg laying behavior

– After mating, snail pulls egg string with mouth, winds it in a

loose ball, and attaches it to an object

– When given ELH, snail exhibits all behaviors even without

mating

32.1 Nature versus Nurture: Genetic Influences

• Experiments with Humans

– Twin Studies

• Look at characteristics of twins raised apart

• Many share common preferences in food, activity patterns,

and mate selection

32.2 Nature versus Nurture: Environmental Influences

• Environmental influences also affect behavior

• Fixed Action Patterns (FAP): specific behaviors elicited by a sign stimulus

• Learning: A durable change in behavior brought about by experience

32.2 Nature versus Nurture: Environmental Influences

• Learning in Birds

32.2 Nature versus Nurture: Environmental Influences

• Learning in Birds

– Imprinting: a simple form of learning

• Young birds follow the first moving object they see

– Sensitive period: time during which imprinting may occur

• Social interactions between parent and offspring during the

sensitive period are important

– Young birds are sensitive to parents vocalization even before

hatching

32.2 Nature versus Nurture: Environmental Influences

• Learning in Birds– Song Learning

• White-crowned sparrows: species-specific song with different dialects; experiments show learning plays a role

• Birds that heard no songs: sang an undeveloped song as adults

• Birds that heard species song: sang in that dialect as long as tape was played during a sensitive period

• Birds that had adult tutor: sang the tutor’s song even if a different species and no matter when tutoring began

32.2 Nature versus Nurture: Environmental Influences

• Associative Learning– A change in behavior that involves an association

between two events.

– Classical Conditioning• The presentation of two different types of stimuli at the same

time causes an animal to form an association between them.

– Operant Conditioning• A stimulus-response connection is strengthened

Classical Conditioning

32.2 Nature versus Nurture: Environmental Influences

• Associative Learning

– Operant Conditioning

• Training an animal by rewarding it

32.3 Adaptive Mating Behavior

• Sexual Selection: adaptive changes that increase ability to attract a mate

• Biological Fitness: ability to produce surviving offspring

32.3 Adaptive Mating Behavior

• Female Choice

– Female animals produce few eggs, choosing a mate is a serious consideration.

– Two Hypotheses:

• Good Genes Hypothesis: females choose mates on basis of traits that improve survival

• Run-away Hypothesis: females choose mates in bases of traits that improve appearance

32.3 Adaptive Mating Behavior

• Female Choice

– The plumage of the male Raggiana birds of paradise may signal health and vigor to the females.

32.3 Adaptive Mating Behavior

• Male Competition– Males can produce many offspring because

continuously produce sperm in large numbers

– Less time and energy invested in reproduction

– Males compete to inseminate as many females as

possible

32.3 Adaptive Mating Behavior

• Male Competition

– Cost / Benefits

• Baboons have dominance hierarchies. Dominant males

mate more often than subordinates. Yet the dominant male

is more likely to be in fights, therefore increasing the chance

of injury.

• Males red deer stags compete for a harem of a particular

territory. The harem master is large and powerful with little

body fat. Little body fat increases the chance of starvation if

food is scarce.

A Male Baboon Displaying Full Threat

Competition Between Male Red Deer

32.3 Adaptive Mating Behavior

• Mating in Humans– Human Males Compete

• Women invest more time and energy in a child biologically– Nine month pregnancy and then lactation

• Men only need to contribute sperm during sex act• Result: men are more available for reproduction than

women– Because more men are available, they must compete

• Humans are dimorphic: men are larger and stronger likely as result of past selection by females

– Males pay a price. The average life span is seven years less than females.

32.3 Adaptive Mating Behavior

• Mating in Humans– Females Choose

• In one study, the ability to achieve financial success was found to be the most preferred trait by females

• Other studies have shown that facial body symmetry is important

– Men Also Have a Choice• Men prefer youthfulness and attractiveness in females, signs

that their partner can provide them with children.• By choosing younger women, older men can increase their

fitness.

32.4 Sociobiology and Animal Behavior

• Sociobiology applies the principles of evolutionary biology to the study of social behavior in animals.

• Hypothesis: Living in a society has a greater reproductive benefit than reproductive cost.

32.4 Sociobiology and Animal Behavior

• Benefits of Group Living– Helps an animal avoid predators, rear offspring, and

find food.

• Disadvantages to Group Living– Competition among members of the group for

resources and exposes group members to illnesses and parasites.

32.4 Sociobiology and Animal Behavior

• Sociobiology and Human Culture

– Humans live in organized societies.

– The culture of a human society involves a wide

spectrum of customs.

– The earliest organized societies may have been the

“hunters-gatherers.”

– A predatory lifestyle likely encouraged the evolution of

intelligence and the development of language.

32.4 Sociobiology and Animal Behavior

• Altruisms versus Self-Interest– Altruism includes behaviors that sacrifice the

individual for the benefit of the group– Inclusive fitness of an individual includes personal

reproductive success as well as that of relatives• Measured by how many genes individual contributes to next

generation

• Helpers at the Nest– Minimal short-term reproductive sacrifice made to

maximize future reproductive potential– Helper contributes to survival of kin

Inclusive Fitness

32.5 Animal Communication

• Communication: An action by a sender that influences the behavior of the receiver– Chemical Communication: Pheromones

• Powerful chemical signals passed in low concentration

• May be released into the air or used in territory marking

– Auditory Communication• Very rapid and can be modified for specific situations

– Visual Communication• Most used by diurnal species-must be able to be seen

• Plumage, courtship “dances”, aggressive displays, etc.

– Tactile Communication• Occurs when one individual touches another

Use of a Pheromone(Chemical Communication)

A Chimpanzee with a Researcher(Auditory Communication)

Visual Communication

Communication Among Bees(Tactile Communication)